You are getting a hard time here OP. If you have never employed a nanny before it can be hard to understand what they do and do not do. Ultimately, you really need to think about what would be helpful for you and set those guidelines when you are interviewing.
Being a nanny is a real job and that comes with time for a lunch break and tea break throughout the day but as I would not take a three hour break at my office job, the nanny does not need a three hour break during their day as well.
We have a nanny and I have made it clear that I expect her to take at least an hour to eat lunch and relax when the children are napping and she is of course welcome to tea breaks during the day too. We provide food and tea/coffee for our nanny as well.
But once her lunch break is over (an hour) she is expected to wash and fold kids laundry (she can do this while they play too if she is in the same room as them, so doesn't need to be done), make baby food, prep art projects, sensory games, clean up baby toys and help toddler clean up their space. When we come home from the day we expect bottles to be washed and clean and any dishes from lunch clean and put away + any kitchen mess that was made while we were away to be clean.
In return, we would never leave our house messy, we make sure the dishwasher is unloaded prior to nanny arriving and that our breakfast things are clean and put away. This takes a lot of planning our end, we wake up early before the kids and deal with our chores so that when nanny arrives, she arrives to a clean house.
Nanny should not be expected to clean messes that did not happen on her watch. I do expect that her time is used efficiently though and that she is using any downtown that isn't a tea or lunch break to plan fun things for the children or prep their meals or snacks.